starting a old project

ive been working on a pps-43 for years and been hung up babysitting my granddaughter. ive got a receiver that need the denile bar in it but i need it straight and true. plan on using key steel and taping it to put a scope mount on it a weaver or pictanny, excuse the piss poor spelling. after i get the trunnion in it can anyone put the bar in it and just drill the rail holes, ill tap it? how much?

right but i need the denial bar in and true with the receiver so i can drill and tap it for a rail to mount scope or laser on it and thats what im asking if anyone can mount the denial bar true with the receiver. havenot mounted trunnion in it because you atr right but still need to mount the denial bar corrctly first..i can eye ball it but as bad as my eyes are i would have it pointing east and shoot myself in the butt. could u place the bolt in it and tack weld the ends and then plug weld the rest of the denial bar in it? thet woul be about as true as i need it wouldnt it?

The KP44 receiver blanks, which are virtually identical to the PPs43 ones except for the magwell area, use a pressed in indentation along the top to act as the denial bar. If you can't do that, I assume you have a drill press? Place the upper in your vise and square it up. Drill a series of holes through the top the width of your denial bar, sliding the upper through the vise jaws as you make each hole. Or use a cross slide vise if you have one. File and Dremel the series of holes to form a slot, or use an end mill in your press with a cross slide vise. Place the bar in the slot with a thin spacer on top of the bolt slot to give clearance and weld it up. Straight.